Added to the Mat3 the possibility to be constructed from a translation vector. Added tests.

src/matrix.rs

@@ -159,6 +159,34 @@ impl<S> Matrix3<S> {
 }
 
 impl<S: BaseFloat> Matrix3<S> {
+    /// Create a homogeneous transformation matrix from a translation vector.
+    #[inline]
+    pub fn from_translation(v: Vector2<S>) -> Matrix3<S> {
+        #[cfg_attr(rustfmt, rustfmt_skip)]
+        Matrix3::new(
+            S::one(), S::zero(), S::zero(),
+            S::zero(), S::one(), S::zero(),
+            v.x, v.y, S::one(),
+        )
+    }
+
+    /// Create a homogeneous transformation matrix from a scale value.
+    #[inline]
+    pub fn from_scale(value: S) -> Matrix3<S> {
+        Matrix3::from_nonuniform_scale(value, value)
+    }
+
+    /// Create a homogeneous transformation matrix from a set of scale values.
+    #[inline]
+    pub fn from_nonuniform_scale(x: S, y: S) -> Matrix3<S> {
+        #[cfg_attr(rustfmt, rustfmt_skip)]
+        Matrix3::new(
+            x, S::zero(), S::zero(),
+            S::zero(), y, S::zero(),
+            S::zero(), S::zero(), S::one(),
+        )
+    }
+
     /// Create a rotation matrix that will cause a vector to point at
     /// `dir`, using `up` for orientation.
     pub fn look_at(dir: Vector3<S>, up: Vector3<S>) -> Matrix3<S> {

tests/matrix.rs

@@ -358,6 +358,14 @@ pub mod matrix3 {
         assert!(Matrix3::from_value(6.0f64).is_diagonal());
     }
 
+    #[test]
+    fn test_from_translation() {
+        let mat = Matrix3::from_translation(Vector2::new(1.0f64, 2.0f64));
+        let vertex = Vector3::new(0.0f64, 0.0f64, 1.0f64);
+        let res = mat * vertex;
+        assert_eq!(res, Vector3::new(1., 2., 1.));
+    }
+
     mod from_axis_x {
         use cgmath::*;